Magnetic chuck.



l.. W. DOWNES & R. C. PATTON.

MAGNETIC CHUCK.

APPL'lcATloN FILED 1uNE29. 191e.

1,232,5 1 2. l Pamd July 10, 1917.

2 SHEETS-SHEET l.

5mm/wicca Zoals /jDozaffcs L. W. DUWNES I R. C. PATTON.

MAGNETIC CHUCK.

APPLICATION FILED IuNE 29. Isls.

1,232,512. Patented Ju1y10,1917.

2 SHEETS-SHEET 2.

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IUNITED sTATEs PATENT OEEIOE.

LOUIS W. DOWNES AND RALPH CLIFTON PATTON,

0F PROVIDENCE, RHODE ISLAND,

ASSIGNORS TO D & W FUSE COMPANY, OF PROVIDENCE, RHODE ISLAND, A CORPORA-TION OF RHODE ISLAND.

MAGNETIC CHUCK.

Specification. of Letters Patent.

Patented lily 10, 1917.

Application filed June 29, 1916. Serial No. 106,579.

and RALPH CLIFTON PATTON, citizens of the United States, and residentsof Providence, in the county of Providence and State of Rhode Island,have invented certain new and useful Improvements in Magnetic Chucks, ofwhich the following is a specication.

This invention relates to magnetic chucks or holding devices moreparticularly adapted for holding small pieces of work to be operatedupon, but the same is adapted for holding work of any form.

The primary object of this invention is to provide such a chuck orholding device, with a face plate having a plurality of alternate fluxcarrying members and nonmagnetic gaps between its center pole and itsouter iiuX carrying frame, whereby the undesirable leakage of magneticflux present in all other types of this class of chucks which results ina loss of holding power, is

here reduced to the very minimum.

A further object of the invention is the forming of the face plateseparate from the body portion and removably securing the same thereto.

A still further object of the invention is the provision of a chuckformed of a p lurality of magnetic units assembled in a single inclosingflux conducting frame to operate in conjunction with each other upon thework.

With these and other objects in view, the invention consists of -certainnovel features of construction, as will be more fully described, andparticularly pointed out in the appended claims.

In the accompanying drawings:

Figure 1-4- is a plan view showing the face of the chuck and thearrangement of the alternate uX carrying members and magneticinsulations separating the center pole from the Outer frame or otherpole.

Fig. 2w is a side elevation partly in section illustrating theconstruction whereby the face plate is formed separate and subsequentlysecured to the body of the chuck.

Fig. 3 is a sectional view on line 3-3 of Fig. 1.

Fig. tis a top view showing a chuck formed of a plurality of magneticunits assembled together in a single flux carrying frame.

Fig. 5- is a side elevation of the chuck shown in Fig. 4L partly insection.

Fig. 6* is a face view of a chuck member made in a circular form andhaving a plurality of alternate magnetic insulations and sinuous fluxcarrying members separating its center pole from its outer frame orpole. l

Referring to the drawings, 10 designates `the body portion 4constructedin the form of a trough-shaped receptacle and formed of magnetic fluxcarrying'material such as cast iron or the like. In the middle portionof this body is formed a core 1l of diferent material such as wroughtiron or the like for the purpose of increasing the magnetic influence Oraction of the chuck upon the work. This central core is preferablyconnected to the base of the body portion by being cast therein.

A suitable magnetic wire coil 12 is carried in this frame 10 and is laidabout this central core 11.

A feature of our improved chuck is in the construction of the face plate13. This plate is preferably formed separate and independent of the bodyportion of the chuck, and comprises essentially an outer frame member14, a central pole member 15 and a plurality of intermediate independentnesting magnetic flux conducting frames or rings 16 spaced apart and setone within and perfectly parallel with the other, and the spaces betweenthese frames are filled with non-magnetic material such as lead, Babbittmetal or other suitable substance.

A plurality of pins 18 of low magnetic permeability such as nickelsteel, bronze or other suitable material, are passed through from theouter frame inward through all of the intermediate frames andinsulations into the center pole member 15, whereby all of these membersare rigidly locked together to prevent them from being forced out ofposition, even if a piece of heavy work should be accidentally droppedupon th'e face of the chuck. After this face plate has been so formedand finished on its top and bottom surfaces, it is secured tothe body.

the outer frame 14 with the corresponding portion 10 of the body member.

By this construction, it will be noted that by the provision of aplurality of non-magnetic gaps arranged in series magnetically thedesirable fiuX leakage between the central pole and the outer fiuXcarrying frame is reduced to the minimum. When the work which isfrequently in small pieces, is distributed about the face of the chuckin such a manner as to bridge the gaps, the magnetic flux travels upwardthrough the core 1l, central pole 15, across the work a as it bridgesthe gaps, into the different intermediate ra-mes and then down throughthe outer wall of the body portion as best illus- 4 trated by the arrowsin Fig. 3.

When work is placed. on the chuck in such a way that a portion only ofthe entire number of gaps are bridged, then `the total fluX willtraverse this work and the reluctance of the magnetic circuit islessened in proportion to the number of non-magnetic gaps so bridged.

When no work is on the chuck face, the total amount of leakage must beacross the several gaps in series.

It is found in practice in some instances, particularly Where theintermediate frames are straight, that narrow straight bars of the sameor less width than the frames placed upon the chuck to be operated upon,would not be held firmly as the work .must bridge one or more of thegaps to be affected by the magnetism. l

In order to obviate this difiiculty, we have formed these frames so thatportions of them are sinuous or arranged to follow a zigzag course asillustrated in Fig. 1 thereby rendering the chuck capable of operatingmore effectively upon the work of a greater variety of shapes.

The form of construction illustrated in Figs. 4 and 5 enables us to makechucks of different sizes by the use of but a single set of castingpatterns, for the reason that the center poles 22 and intermediateframes 23 are duplicated in the several magnetic units. rlhe patternsfor the outer frame 21 may be made in se arate sections if desired,' andany num er of these pattern sections may be used to cast a frame of thedesired dimensions to receive the required number of magnetic units.Then again by our construction, it is possible to make a single patternof the outer frame and face frame, of the largest size and then use thispattern for the smaller sizes by simply stopping off that portion notdesired, during the molding operation.

1t will be seen by this construction that the cost of producing chucksof different sizes may be reduced to the minimum.

rlhe chucks constructed as described above consist of a plurality ofmagnetic units,

follow a sinuous or zigzag course in a general circular direction ifdesired so that if a piston ring or the like should be applied to thechuck, it could not be placed on its surface in any `position without-bridging one or more ofthe non-magnetic gaps.

The face plate of our improved chuck may be constructed very easily andwith small expense by first casting all'of the various rings or framesin one piece being connected together by a thin web or sheet of metal onone side only (not shown). Suc-h a casting when taken from amold will bein reality a thick plate with a number of deep grooves on one side intowhich grooves is poured a soft non-magnetic filling metal or materialwhich is usually employed for filling such magnetic gaps. The plate willthen be machined on both sides to secure true surfacing. The connectingweb which is used merely for the sake of .supporting the ring whilebeing cast will be removed in the surfacing operation thereby leavingthe intermediate rings or frames entirely insulated from each -other andproviding a plurality of alternate fluX carrying members and magneticinsulations which separate the center pole from the outer frame thusreducing to the minimum the leakage of magnetic flux. rl`he device isextremely simple, practical and inexpensive in construction andeffective inits operation.

We have shown and described one illustrative embodiment of our inventionbut we desire it to be understood that although specific terms areemployed they are used in a generic and descriptive sense and not forthe purpose of limitation, the scope of the invention being defined bythe appended claims.

`We claim:

1. A magnetic chuck comprising a body portion carrying a magnetic coil,an independent removable face plate attached to said body having acentral pole and an outer frame, and a plurality of alternateindependent fluX-carrying frames and nonmagnetic portions intermediatesaid pole and outer frame, and tie bars between said portion carrying amagnetic coil, an indeinterposed between said frames, and independentace plate removably attached t0 pendent means for mechanicallyconnecting said frame, said plate having a central pole together Saidpole and all of said frames. 10

and an outer frame and a plurality of inde- In testimony whereof WealiiX our sig- 5 pendent spaced apart parallel sinuous natures.

frames located intermediate said pole and LOUIS W. DOWNES.

outer frame, non-magnetic portions being RALPH CLIFTON PATTON.

